Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Quercus mulleri is a microendemic oak from the Sierra Sur of Oaxaca and is considered in IUCN red list of threatened species as “critically endangered”, however, due to lack of current information on the species, the conservation status of its populations is unknown, and therefore it has not been possible to allocate an appropriate risk category to it. This work represents the first report of Q. mulleri after more than 60 years of its last taxonomic classification, with the aim to analyze its abundance, distribution and genetic diversity to propose conservation strategies. The species was re-localized, and we found that it is restricted to a small region in Sierra Sur and is fragmented and geographically isolated. Species populations have low individual frequency by size class (6.13 ± 5.6). Allelic diversity values, using five microsatellite regions from the quru-GA series, were low (AT=22 y Ao=4.4), but genetic diversity values were relatively high (Ho=0.54), suggesting that the population went through a bottleneck. Results indicate that Q. mulleri is a vulnerable species, and since in its distribution area there is an ongoing habitat loss plus its population fragmentation, its permanence could be at risk, and for this we recommend including this species in the Norma Oficial Mexicana 059 as “Species at Extinction Risk”.

Revealing the effect of mixed beech and hornbeam stands on herb layer diversity is essential for sustainable forestry and biodiversity conservation since little is known in Hyrcanian forests. So, we studied the effects of such stands on understory diversity and soil physico-chemical properties in Hyrcanian forests of Iran. Forty sampled plots were established by random systematic sampling method with a regular 100 m × 200 m grid. At each sample point we recorded species identity and percent cover of each tree layer and herb layer species within plots of size 400 m2 (20 m × 20 m) and 100 m2 (10 m ×10 m) respectively. Soil samples were taken from 0 cm -10 cm and 10 cm - 30 cm soil depths. Cluster analysis was used to classify the samples based on the floristic composition data. Also detrended correspondence analysis (DCA) method was employed to assess the relationship between vegetation and environmental variables. There was no significant difference in terms of species richness, and diversity between mixed beech stands and hornbeam stands, but cluster analysis indicated that these stands were separated in two different groups based on herb layer species composition. DCA results showed that litter thickness, soil texture, total nitrogen, and organic carbon in the first layer were considered effective environmental variables in the distribution of sample plots in two stands. We observed that tree layer composition and soil characteristics were crucial contributors to variations of understory species composition which may be changed by forest management approaches over time. Tree layer composition and soil attributes can be considered effective factors for controlling and assessment of understory plant species composition. These findings could provide guidelines for conserving plant species diversity within any framework of sustainable forest management in Hyrcanian forests.

In Mexico, Pinus oocarpa Schiede ex Schltdl is one of the forest tree species of major ecological (for its wide geographical distribution), and economic importance (for the resin extraction in natural stands). More intensive exploitation will require establishing commercial plantations, which could be multipurpose: for resin tapping and wood. The present study aimed to explore the genetic control (heritability) of the growth characteristics for total height (HGT), stem base diameter (DIAM), diameter at breast height (DBH) of half-sib progenies from trees originally selected for its resin yield. All these in order to assess the feasibility of a multipurpose breeding program. In 2011, it was established a progeny trial in Michoacán, Mexico, with 27 open-pollinated half-sib families in an experimental design of 10 randomized complete blocks. Five years after its establishment, the mean values were HGT = 5.5 m, in DIAM of 13.4 cm, and DBH = 10.4 cm. We found statistically significant differences among families for all the characteristics. Narrow-sense heritability at individual level (h2i) was: HGT = 0.15, DIAM = 0.22, and DBH = 0.17; at family mean level (h2f) it was 0.44, 0.54, and 0.47, respectively. At an intensity of selection of the best individuals of i = 1.4, the genetic gains for HGT, DIAM, and DBH were 3.9, 5.2, and 5.0%, respectively. If, in the future, it is demonstrated that there is an association between diameter and resin yield, it would be feasible to increase both traits through the selection of the best individuals with the greatest diameters.

The natural durability of the wood is an excellent characteristic for the use of wood parts under proper and efficient conditions of use. This work aimed to evaluate the natural resistance of six wood forest species to xylophagous termites in field conditions. The woods studied were Carapa guianensis Aubl, Myracrodruon urundeuva Allemão, Cedrella sp., Hymenaea courbaril L., Nectandra sp. and Manilkara elata (Allemão ex Miq.) Monach.  Test samples with dimensions of 7.2 cm × 1.3 cm × 0.9 cm (longitudinal × radial × tangential) were made from each wood species. They remained exposed for 40 days under the action of Nasutitermes corniger Motschulsky termites in a food preference test, Carapa guianensis wood presented greater mass loss and susceptibility to attack by N. corniger. On the other hand, the species Cedrella sp. and Nectandra sp. showed intermediate values among the others to the analyzed aspects. The woods of Carapa guianensis, Hymenaea courbaril and Manilkara elata stood out in the grade values attributed to the wear, as well as the low susceptibility. Therefore, these latter woods are best suited for use in order to promote their efficient use, minimize damage caused by exposure to xylophagous termites and maximize the useful life and safety of the timber product.

Mosses represent a non-timber forest resource with economic importance in Central Mexico during Christmas season. Some places and species have been studied but in Tlaxcala state there is no information about the origin, quantity harvested, and species with commercial importance in this season. For this reason, licenses for commercial harvest for the years 2005 to 2008 from Secretaría de Medioambiente y Recursos Naturales-Tlaxcala were reviewed, and four farms were visited to recollect mosses on three 20 cm × 20 cm samples, and three samples were purchased in local markets of the main cities in Tlaxcala state for complementary information. Surface area and fresh weight were calculated only with market samples and compared with commercial licenses. The Tlaxco region had most of the licenses, and in general the declared area for commercial harvesting is from 10 ha to 167 ha and the fresh weight is from 10 t to 65 t. The commercial value of the samples in the markets for the size is from 22 MXN/m2 to 52 MXN/m2 and for the calculated fresh weight is of 15.89 MXN/kg to 64.10 MXN/kg, with a commercial value calculated of 372 500 MXN/ha, 40 000 MXN/t; from the harvesting licenses, ot was determined that there is an annual extraction capacity of 1.63 t/ha. From the samples recollected in the field and the markets a total of 14 species has been identified, detecting that Thuidium delicatulum subsp. delicatulum is common in all samples, but Hypnum amabile is present only in the samples from the markets.

The population structure and the patterns of spatial distribution and correlation among developmental stages of Hintonia latiflora, a species threatened in Mexico by the commercial harvest of its bark, are documented. Six plots (three in harvested sites and three in not harvested ones) of 20 m × 100 m were established for the census of all plants and they were categorized into three stages of development based on the total height and basal diameter; all individuals were located by their cartesian coordinates. The population structure was analyzed by a density histogram; whereas bias and kurtosis were used to determine the harvest effect on size categories. Univariate and bivariate spatial patterns were determined using Ripley's L(t) and L12(t) functions, respectively, and the statistical significance was 99% using Monte Carlo simulations. Density between harvested sites vs. not harvested was statistically different (p < 0.013), but the population structure was similar, with a positive asymmetric distribution pattern (S3 = 0.947 and S3 = 1.063) and leptokurtic (S4 = 2.006 and S4 = 2.400). The univariate distribution pattern in all cases was aggregated (L(t) > 0), whereas the spatial correlation in populations subject to debarking reflected a combination between independence and spatial attraction at different distances. This information provides a basis for the sustainable management of H. latiflora and represents the first study in Mexico that analyzes the debarking of a medicinal resource on its population-spatial structure.

El bosque tropical caducifolio está altamente amenazado y transformado a causa de las actividades agrícolas en Chiapas; sin embargo, se conoce poco acerca de su dinámica sucesional y potencial de regeneración. El objetivo de la investigación fue evaluar la capacidad regenerativa de los bosques secundarios a través de los cambios en la riqueza, diversidad, composición y estructura en una reserva forestal de la Depresión Central de Chiapas. Se establecieron 20 unidades de muestreo (UM) de 1000 m2 en bosques con diferentes edades de abandono (C10, C19, C35 y ˃ C40, que representan 10 años, 19 años, 35 años y 40 años, respectivamente), en las que se midieron todos los individuos ≥ 5 cm de diámetro normal (DN). Se compararon en cada condición atributos de estructura y diversidad mediante análisis de varianza y prueba de comparación de medias Tukey (p < 0.05) y la composición florística a través de análisis de ordenación y clasificación. Se registró un total de 142 especies agrupadas en 96 géneros y 41 familias. Leguminosae fue la familia con más especies e individuos. Las especies con mayores abundancias relativas fueron Montanoa tomentosa (5.1%) y Tecoma stans (5%). Se encontraron diferencias significativas (p < 0.05) en la riqueza acumulada, diversidad (Shannon–Weiner Hˊ y 1D), densidad de individuos (ind ha-1), altura máxima (m), área basal (m2 ha-1) y biomasa aérea (Mg ha-1). El procedimiento de análisis de varianza multivariado con permutaciones indicó diferencias significativas (p < 0.05) en la composición de especies entre las condiciones tempranas (C10 y C19) y las más avanzadas (C35 - C40). Se concluyó que la estructura y composición florística del bosque secundario se recupera lento (baja resilencia), por lo que se requiere implementar actividades conducentes a su conservación en el corto plazo.

Forestiera phillyreoides is a species of wide distribution in semi-arid and subtropical areas of the country. Despite being a common species, there is no information about its propagation. Therefore, the objective was to generate information about its fruiting, its germination under different pre-germinative treatments and the growth of seedlings in the nursery. A review of herbarium and field trips was carried out to know the fruiting. Eight pre-germinative treatments were evaluated: control, 24 h water immersion, sulfuric acid immersion (3 min, 6 min, 9 min and 12 min), manual endocarp removal plus 24 h immersion and 24 h immersion in 500 ppm of GA3. Seedlings were cultivated for seven months, at the end of the period, the height, diameter, the aerial dry weight/root dry weight ratio (PSA/PSR), robustness index and Dickson quality index were calculated. Fruiting occurs during the months of March to June. The endocarp removal treatment had the highest germination percentage (95 ± 4.08), a positive response to sulfuric acid treatments was presented, the GA3 treatment had negative effects on germination. The seedlings reached a height of 31.65 cm ± 5.01 cm and a diameter of 5.13 mm ± 0.34 mm, the PSA / PSR values (1.02 ± 0.17) indicate drought resistance. The treatments that remove or degrade the endocarp are the most appropriate to achieve better germination. At seven months it reached the necessary parameters for use in reforestation. The information generated provides the basis for the propagation of F. phillyreoides.

The aim was to determine the better allometric model with mixed effects that describes the total height-normal diameter (A-d) relation for Lysiloma latisiliquum trees in Quintana Roo, Mexico.  The slenderness index (IE: A/d) and six local models were adjusted from 2214 pairs of A-d data obtained from the National Forest and Soil Inventory (2004-2009); to improve the fit and after the selection of the best model, the covariates conglomerate, canopy diameter (dc), clean stem height (Af), municipality (M), primary vegetation type (Vp) and altitude, were included under the mixed effects models approach. The IE decreases as the dimensions of the trees increase. The Hossfeld's model (1822) with the inclusion of the conglomerate covariate in the parameter  proved to be the best for describing the A-d, since it explains more than 70% of the sample variability and has a bias of 0.00013 m. Furthermore, when comparing the estimates with data from an independent sample, no significant differences were observed at a 99% level of reliability. The insertion of the different environmental and growth conditions modifies the allometric relationship A-d in Lysiloma latisiliquum in the tropical forests of Quintana Roo, Mexico, and the mixed models showed to be an option of statistical improvement and precision in the estimation.

Há mais de um século as espécies de Pinus estão presentes no Brasil, com destaque para o Pinus taeda, com aplicações em diversos setores. Entretanto o Pinus glabra, objeto deste estudo, não conta com muitas informações sobre o potencial tecnológico de sua madeira. Assim o objetivo do estudo é inferir sobre a qualidade da madeira do P. glabra para produção de polpa celulósica, comparando-a ao P. taeda, principal espécie empregada para fabricação de polpa celulósica de fibra longa no Brasil. Para isso foram abatidas quatro árvores, das quais retiraram-se discos visando a caracterização física, química e anatômica da madeira. Em relação a densidade básica (massa seca/volume verde), observaram-se os valores médio e ponderado de 0,421 g/cm-3 e 0,424 g/cm-3, respectivamente, o que a classifica como de baixa densidade. Na caracterização anatômica obtiveram-se os valores médios de comprimento de 3,14 mm, largura de 27,18 µm, diâmetro do lúmen de 15,39 µm e espessura da parede de 5,89 µm dos traqueídeos, que resultaram em 44,72%, 55,28%, 0,90 e 120,72 para os parâmetros de fração parede, coeficiente de flexibilidade, índice de Runkel e índice de enfeltramento, respectivamente. Para a composição química foram observados baixos teores de cinzas (0,25%) e extrativos (1,91%), e teores intermediários de lignina (29,93%) e holocelulose (67,91%). Desta forma a madeira de P. glabra apresenta potencial para produção de polpa celulósica, o qual deve ser comprovado por meio de ensaios de polpação.